Mobile devices in this increasingly more and more connected world not only need frequent, periodic recharging, but also to exchange data with other devices or the Internet on a regular basis.
The data communications between a mobile device and another device is typically achieved by a cable, such as an USB cable, an IEEE 1394 cable, an Ethernet cable, or a proprietary serial link, as well as by wireless RF links. As with electrical interconnections, any cable-based data link entails precise and tedious alignment of electrical contact pins to enable data communication. Thus the mobile device has to have a fixed spatial relationship to the other device while data transfer is taking place. This greatly limits the mobility and the utility of the mobile device while data transfer is in progress. Wireless data communications does not require pin arrangement, but because of the intrinsically unreliable nature of wireless links in general, data transfer is not exactly a plug-and-play affair even for those mobile devices with built-in wireless data links. Some wireless data transfer methods, such as infrared communications, still requires certain degree of alignment since the infrared signal is transmitted over a fairly narrow angle. Infrared data link also is strictly one-to-one data link and can't support simultaneous data communications among multiple mobile or stationary devices.
Modern high-speed wireless standards, such as IEEE 802.11 a/b/g, and soon to be rectified UWB (ultra wide band), can provide reasonably high data transfer rates. However, since the data is transported over the air, both security and interference can become an issue. Although all high-speed wireless data communication standards provide ample security measures to safeguard the confidentiality of the data being transferred as well as protecting the mobile device from malicious attacks from the air, they all add a layer of complication which compromises their usability. Wireless links are also susceptible to interferences from natural or manmade RF sources. For example, IEEE 802.11 b/g is famous for its susceptibility to RF leakage from microwave oven that operates within the same spectrum. And interference from adjacent WiFi hotspots and other IEEE 802.11 access points can interrupt data communication and even cause the mobile device to drop its wireless connections on occasion.
Therefore, there exists a need for an alternative to both the cable-based data transfer and the wireless data communication approaches.